1221003155 has 8 divisors (see below), whose sum is σ = 1551392352. Its totient is φ = 919343488.

The previous prime is 1221003151. The next prime is 1221003187. The reversal of 1221003155 is 5513001221.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1221003155 - 2² = 1221003151 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221003151) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7182287 + ... + 7182456.

It is an arithmetic number, because the mean of its divisors is an integer number (193924044).

Almost surely, 2^1221003155 is an apocalyptic number.

1221003155 is a deficient number, since it is larger than the sum of its proper divisors (330389197).

1221003155 is a wasteful number, since it uses less digits than its factorization.

1221003155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14364765.

The product of its (nonzero) digits is 300, while the sum is 20.

The square root of 1221003155 is about 34942.8555644784. The cubic root of 1221003155 is about 1068.8225190239.

Adding to 1221003155 its reverse (5513001221), we get a palindrome (6734004376).

The spelling of 1221003155 in words is "one billion, two hundred twenty-one million, three thousand, one hundred fifty-five".